A light sensor using infrared ray is known to be used in remote-control devices such as, for example, remote controllers of televisions and automatic doors, three dimensional shape measuring apparatuses are known. Recently, it has been used for various applications including inter-vehicular distance detection sensors used in automatic braking technique of automobiles, and a range imagery sensor used in gesture input controllers such as “Kinect (registered trade mark)” manufactured by U.S. Microsoft Corporation in various fields.
Usually, signal sources and light-receiving elements of these light sensors are provided with a light filter, which blocks visible light and transmits infrared ray for the purpose of removing noise due to visible light and in view of design. As the light filter, for example, light filters obtained from a composition containing a blue colorant, a yellow colorant and a red colorant are known (Patent Document 1).